"Design" of boron-based compounds as pro-nucleophiles and co-catalysts for indium(I)-catalyzed allyl transfer to various Csp3-type electrophiles

Hai Thanh Dao; Uwe Schneider; Shū Kobayashi

doi:10.1002/asia.201100096

"Design" of boron-based compounds as pro-nucleophiles and co-catalysts for indium(I)-catalyzed allyl transfer to various Csp3-type electrophiles

Chem Asian J. 2011 Sep 5;6(9):2522-9. doi: 10.1002/asia.201100096. Epub 2011 Jul 4.

Authors

Hai Thanh Dao¹, Uwe Schneider, Shū Kobayashi

Affiliation

¹ Department of Chemistry, School of Science, The University of Tokyo, The HFRE Division, ERATO (Japan) Science and Technology Agency (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

PMID: 21728247
DOI: 10.1002/asia.201100096

Abstract

We have recently uncovered a general indium(I)-catalyzed method for allylations and propargylation of acetals and ketals with a water- and air-stable allyl boronate. By using a more reactive allyl borane, we have successfully extended this methodology to the more challenging C-C coupling with ethers. Herein, we report an improved methodology for the indium(I)-catalyzed allylation of acetals and ethers, through combination of the allyl boronate with a commercially available "hard" Lewis acid, B-methoxy-9-BBN (BBN=borabicyclo[3.3.1]nonane), as an effective co-catalyst. Significantly, our work highlights for the first time the correlation between the Lewis acidity of "electrophilic" boron-based compounds and their "nucleophilic" reactivity in Csp(3)-Csp(3) couplings, catalyzed by a "soft" low-oxidation main group metal. In addition, we also report several applications of these methodologies to the selective synthesis of various carbohydrate derivatives.